Gradient cooling manifold assembly having additively manufactured manifolds

ABSTRACT

A manifold for a gradient coil cooling manifold assembly of a MRI system includes a first main fluid passage defined by a first wall. The manifold also includes a first set of secondary fluid passages coupled to the first main fluid passage and defined by respective walls, wherein the first wall of the first main fluid passage and the respective walls of the first set of secondary fluid passages form barb connectors configured to couple to respective hoses. The manifold is formed as a single integral piece.

BACKGROUND

The subject matter disclosed herein relates to a magnetic resonanceimaging (MRI) system and, more particularly, to a gradient coolingmanifold assembly having additively manufactured manifolds.

Non-invasive imaging technologies allow images of the internalstructures or features of a patient/object to be obtained withoutperforming an invasive procedure on the patient/object. In particular,such non-invasive imaging technologies rely on various physicalprinciples (such as the differential transmission of X-rays through atarget volume, the reflection of acoustic waves within the volume, theparamagnetic properties of different tissues and materials within thevolume, the breakdown of targeted radionuclides within the body, and soforth) to acquire data and to construct images or otherwise representthe observed internal features of the patient/object.

During MRI, when a substance such as human tissue is subjected to auniform magnetic field (polarizing field B₀), the individual magneticmoments of the spins in the tissue attempt to align with this polarizingfield, but precess about it in random order at their characteristicLarmor frequency. If the substance, or tissue, is subjected to amagnetic field (excitation field B1) which is in the x-y plane and whichis near the Larmor frequency, the net aligned moment, or “longitudinalmagnetization”, Mz, may be rotated, or “tipped”, into the x-y plane toproduce a net transverse magnetic moment, M_(t). A signal is emitted bythe excited spins after the excitation signal B₁ is terminated and thissignal may be received and processed to form an image.

When utilizing these signals to produce images, magnetic field gradients(G_(x), G_(y), and G_(z)) are employed. Typically, the region to beimaged is scanned by a sequence of measurement cycles in which thesegradient fields vary according to the particular localization methodbeing used. The resulting set of received nuclear magnetic resonance(NMR) signals are digitized and processed to reconstruct the image usingone of many well-known reconstruction techniques.

The magnetic field gradients are generated by gradient field coils in agradient coil assembly. The gradient coil assembly generates heat duringimaging (e.g., due to eddy currents and resistive heating). Differenttypes of cooling (e.g., fluidic cooling) are typically utilized tominimize heating of the gradient coil assembly. However, as the bore ofMRI systems increase, minimizing the heating of the gradient coilassembly becomes more challenging. In addition, manifold assemblies forproviding the fluid to cool the gradient coil assembly are costly,occupy a large footprint, and are subject to a higher risk of mechanicalfailure (e.g., due to the number of connections and the system demandson the manifold assemblies).

BRIEF DESCRIPTION

A summary of certain embodiments disclosed herein is set forth below. Itshould be understood that these aspects are presented merely to providethe reader with a brief summary of these certain embodiments and thatthese aspects are not intended to limit the scope of this disclosure.Indeed, this disclosure may encompass a variety of aspects that may notbe set forth below.

In one embodiment, a manifold for a gradient coil cooling manifoldassembly of a MRI system is provided. The manifold includes a first mainfluid passage defined by a first wall. The manifold also includes afirst set of secondary fluid passages coupled to the first main fluidpassage and defined by respective walls, wherein the first wall of thefirst main fluid passage and the respective walls of the first set ofsecondary fluid passages form barb connectors configured to couple torespective hoses. The manifold is formed as a single integral piece.

In one embodiment, a gradient coil cooling manifold assembly of a MRIsystem includes a plurality of hoses. The gradient coil cooling manifoldassembly also includes a plurality of additively manufactured manifoldscoupled to the plurality of hoses. Each additively manufactured manifoldof the plurality of additively manufactured manifolds includes a mainfluid passage defined by a wall. Each additively manufactured manifoldof the plurality of additively manufactured manifolds also includes aset of secondary fluid passages coupled to the main fluid passage anddefined by respective walls. The wall of the main fluid passage and therespective walls of the set of secondary fluid passages form barbconnectors configured to couple to respective hoses of the plurality ofhoses.

In one embodiment, a MRI system is provided. The MRI system includes agradient coil assembly including a plurality of gradient coils. The MRIsystem also includes a gradient coil cooling manifold assemblyconfigured to couple to the gradient coil assembly and to regulate atemperature of the gradient coil assembly. The gradient coil coolingmanifold assembly includes a plurality of manifolds. Each manifold ofthe plurality of manifolds includes a main fluid passage defined by awall. Each manifold of the plurality of manifolds also includes a set ofsecondary fluid passages coupled to the main fluid passage and definedby respective walls. The wall of the main fluid passage and therespective walls of the set of secondary fluid passages form barbconnectors configured to couple to respective hoses. Each manifold ofthe plurality of manifolds is formed as a single integral piece.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 illustrates an embodiment of a magnetic resonance imaging (MRI)system suitable for use with the disclosed technique;

FIG. 2 is a schematic view of an embodiment of a cooling system coupledto a gradient coil assembly of the MRI system of FIG. 1 , in accordancewith aspects of the present disclosure;

FIG. 3 is a perspective view of an embodiment of a gradient coil coolingmanifold assembly coupled to a gradient coil assembly, in accordancewith aspects of the present disclosure;

FIG. 4 is front view of the gradient coil cooling manifold assembly ofFIG. 3 coupled to the gradient coil assembly, in accordance with aspectsof the present disclosure;

FIG. 5 is a perspective view of an embodiment of a manifold of thegradient coil cooling manifold assembly of FIG. 3 (e.g., having two mainpassages), in accordance with aspects of the present disclosure;

FIG. 6 is another perspective view of the manifold in FIG. 5 , inaccordance with aspects of the present disclosure;

FIG. 7 is a perspective view of an embodiment of a manifold of thegradient coil cooling manifold assembly of FIG. 3 (e.g., having two mainpassages), in accordance with aspects of the present disclosure;

FIG. 8 is a perspective view of an embodiment of a manifold of thegradient coil cooling manifold assembly of FIG. 3 (e.g., having a singlemain passage), in accordance with aspects of the present disclosure; and

FIG. 9 is a perspective view of an embodiment of a manifold of thegradient coil cooling manifold assembly of FIG. 3 (e.g., having a singlemain passage), in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

One or more specific embodiments will be described below. In an effortto provide a concise description of these embodiments, not all featuresof an actual implementation are described in the specification. Itshould be appreciated that in the development of any such actualimplementation, as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the present subjectmatter, the articles “a,” “an,” “the,” and “said” are intended to meanthat there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Furthermore, any numerical examples in the following discussion areintended to be non-limiting, and thus additional numerical values,ranges, and percentages are within the scope of the disclosedembodiments.

While aspects of the following discussion are provided in the context ofmedical imaging, it should be appreciated that the disclosed techniquesare not limited to such medical contexts. Indeed, the provision ofexamples and explanations in such a medical context is only tofacilitate explanation by providing instances of real-worldimplementations and applications. However, the disclosed techniques mayalso be utilized in other contexts, such as image reconstruction fornon-destructive inspection of manufactured parts or goods (i.e., qualitycontrol or quality review applications), and/or the non-invasiveinspection of packages, boxes, luggage, and so forth (i.e., security orscreening applications). In general, the disclosed techniques may beuseful in any imaging or screening context or image processing orphotography field where a set or type of acquired data undergoes areconstruction process to generate an image or volume.

Manifold assemblies for providing fluid to cool gradient coil assembliesof MRI systems are costly, occupy a large footprint, and are subject toa higher risk of mechanical failure (e.g., due to the number ofconnections and the system demands on the manifold assemblies).Manufacturing manifold assemblies to meet the system demands for coolinggradient coil assemblies is difficult. Traditional fabricationtechniques are insufficient. For example, copper welded/braze assembliesare too bulky and rigid and, thus, prone to damage. In addition, thecost of a welded assembly is a burden. A machined block style manifoldtakes up too much space and is too heavy. In addition, the machinedblock style includes numerous connections or joints, which increase theamount of potential leak paths. Casting necessitates complex and costlytooling, which limits design iteration.

The present disclosure provides a gradient cooling manifold assembly fora MRI system that includes one or more additively manufactured (e.g.,via direct metal laser sintering) manifolds or manifold modules coupledto flexible rubber hosing. Each manifold module includes at least onemain or primary fluid passage (e.g., inlet or outlet) defined by a firstwall and a set of secondary fluid passages coupled to the main passageand defined by respective walls. The wall of at least one main fluidpassage and the respective walls of the set of secondary fluid passagesform barb connectors or fittings configured to couple to respectivehoses. In certain embodiments, each manifold module includes two main orprimary fluid passages defined by a first wall and a second wall (e.g.physically coupled via one or more structural ribs extending between thefirst and second walls) with each main fluid passage coupled to arespective set of secondary fluid passages having respective walls thatform barb connectors. The one or more main fluid passages and the one ormore sets of primary fluid passages of the manifold module are formed asa single integral piece.

Additive manufacturing's ability to quickly print complex geometriesenables the manifold modules to be optimized to produce maximum flowwith minimal volumetric space, efficient fabrication, assembly, andservice ability. Critical space (e.g., axial space between the manifoldassembly and the gradient coil assembly) is saved by matching themodule's mainline geometry to that of the gradient coil's circular shapeand targeting the branches to their destination. Fabricating thiscomplex geometry would be substantially more difficult with traditionalmodule fabrication techniques. Additive manufacturing allows combiningotherwise separate components into a single part enable to withstand thesystem parameters for cooling a gradient coil assembly of a MRI system.The disclosed embodiments enable less connections in the manifoldassembly, thus, lowering the risk of leaks. In addition, less brazejoints/fittings enables a lower risk of mechanical failure in themanifold assembly. Further, the custom precise geometry enables bettercooling with fewer failures. Even further, the disclosed embodimentsenable a lower cost manifold assembly.

Turning now to the drawings, and referring first to FIG. 1 , a magneticresonance imaging (MRI) system 10 is illustrated diagrammatically asincluding a scanner 12, scanner control circuitry 14, and system controlcircuitry 16. While MRI system 10 may include any suitable MRI scanneror detector, in the illustrated embodiment the system includes a fullbody scanner comprising a patient bore 18 into which a table 20 may bepositioned to place a patient 22 in a desired position for scanning.

Scanner 12 includes a series of associated coils for producingcontrolled magnetic fields, for generating radiofrequency excitationpulses, and for detecting emissions from gyromagnetic material withinthe patient in response to such pulses. In the diagrammatical view ofFIG. 1 , a primary magnet coil 24 (e.g., superconducting magnet coil) isprovided for generating a primary magnetic field, B₀, generally alignedwith patient bore 18. In certain embodiments, B₀ fields on the order of3T to 7T are contemplated, but fields higher than 7T and as low as afraction of a Tesla are also contemplated. A series of gradient coils26, 28 and 30 (e.g., magnetic gradient field coils) are grouped in acoil assembly (e.g., gradient coil assembly) for generating controlledmagnetic gradient fields during examination sequences as described morefully below. A radiofrequency coil 32 is provided for generatingradiofrequency pulses for exciting the gyromagnetic material. In theembodiment illustrated in FIG. 1 , coil 32 also serves as a receivingcoil. Thus, radiofrequency (RF) coil 32 may be coupled with driving andreceiving circuitry in passive and active modes for receiving emissionsfrom the gyromagnetic material and for applying radiofrequencyexcitation pulses, respectively. Alternatively, various configurationsof receiving coils may be provided separate from RF coil 32. Such coilsmay include structures specifically adapted for target anatomies, suchas head coil assemblies, and so forth. Moreover, receiving coils may beprovided in any suitable physical configuration, including phased arraycoils, and so forth.

In a present configuration, the magnet gradient field coils 26, 28 and30 have different physical configurations adapted to their function inthe imaging system 10. As will be appreciated by those skilled in theart, the coils are comprised of conductive wires, bars or plates whichare wound or cut to form a coil structure which generates a gradientfield upon application of control pulses as described below. Theplacement of the coils within the gradient coil assembly may be done inseveral different orders, but in the present embodiment, a Z-axis coilis positioned at an innermost location, and is formed generally as asolenoid-like structure which has relatively little impact on the RFmagnetic field. Thus, in the illustrated embodiment, gradient coil 30 isthe Z-axis solenoid coil, while coils 26 and 28 are the transverseY-axis and X-axis coils, respectively.

The coils of scanner 12 are controlled by external circuitry to generatedesired fields and pulses, and to read signals in a controlled manner.As will be appreciated by those skilled in the art, when the material,typically bound in tissues of the patient, is subjected to the primaryfield, magnetic moments of the nuclei in the tissue partially align withthe field. While a net magnetic moment is produced in the direction ofthe polarizing field, the randomly oriented components of the moment ina perpendicular plane generally cancel one another. During anexamination sequence, an RF frequency pulse is generated at or near theLarmor frequency of the material of interest, resulting in rotation ofthe net aligned moment to produce a net transverse magnetic moment. Thistransverse magnetic moment precesses around the main magnetic fielddirection, emitting RF signals that are detected by the scanner andprocessed for reconstruction of the desired image.

Gradient coils 26, 28 and 30 serve to generate precisely controlledmagnetic fields, the strength of which vary over a predefined field ofview, typically with positive and negative polarity. When each coil isenergized with known electric current, the resulting magnetic fieldgradient is superimposed over the primary field and produces a desirablylinear variation in the Z-axis component of the magnetic field strengthacross the field of view. The gradient coil for each axis generates alinear magnetic field gradient in the direction of that axis. As such,the spatially-varying z-directed magnetic field varies linearly alongthe direction of the gradient coil axis. The three coils have mutuallyorthogonal axes for the direction of their variation, enabling a linearfield gradient to be imposed in an arbitrary direction with anappropriate combination of the three gradient coils.

The pulsed gradient fields perform various functions integral to theimaging process. Some of these functions are slice selection, frequencyencoding and phase encoding. These functions can be applied along theX-, Y- and Z-axis of the original coordinate system or along other axesdetermined by combinations of pulsed currents applied to the individualfield coils.

The slice select gradient determines a slab or cross-section of tissueor anatomy to be imaged in the patient. The slice select gradient fieldmay be applied simultaneously with a frequency selective RF pulse toexcite a known volume of spins within a desired slice that precess atthe frequencies equal to the excitation bandwidth of the RF pulse. Theslice thickness is determined by the bandwidth of the RF pulse and thegradient strength across the field of view.

The frequency encoding gradient is also known as the readout gradientand is usually applied in a direction perpendicular to the slice selectgradient. The frequency encoding gradient encodes positional informationof spins with the plane excited by the RF pulse. In general, thefrequency encoding gradient waveforms comprises of a dephasing lobe thatdephases the spins, and a readout gradient lobe that rephases the spinsat the center of the readout gradient waveform to form an echo. Spinswith a nuclear magnetic moment encoded with a spatially varying phase(as they precess at different frequencies) according to their spatialposition along the gradient field. By Fourier transformation, acquiredsignals may be analyzed to identify their location in the selected sliceby virtue of the frequency encoding.

Finally, the phase encode gradient is generally applied before thereadout gradient and after the slice select gradient. Localization ofspins in the gyromagnetic material in the phase encode direction isaccomplished by sequentially inducing variations in phase of theprecessing protons of the material using slightly different gradientamplitudes that are sequentially applied during the data acquisitionsequence. The phase encode gradient permits phase differences to becreated among the spins of the material in accordance with theirposition in the phase encode direction, similar in principle to thephase accumulated by spins in the readout gradient waveform at differenttime points.

As will be appreciated by those skilled in the art, a great number ofvariations may be devised for pulse sequences employing the exemplarygradient pulse functions described above as well as other gradient pulsefunctions not explicitly described here. Moreover, adaptations in thepulse sequences may be made to appropriately orient both the selectedslice and the frequency and phase encoding to excite the desiredmaterial and to acquire resulting MR signals for processing.

The coils of scanner 12 are controlled by scanner control circuitry 14to generate the desired magnetic field and radiofrequency pulses. In thediagrammatical view of FIG. 1 , control circuitry 14 thus includes acontrol circuit 36 for commanding the pulse sequences employed duringthe examinations, and for processing received signals. Control circuit36 may include any suitable programmable logic device, such as a CPU ordigital signal processor of a general purpose or application-specificcomputer. Control circuit 36 further includes memory circuitry 38, suchas volatile and non-volatile memory devices for storing physical andlogical axis configuration parameters, examination pulse sequencedescriptions, acquired image data, programming routines, and so forth,used during the examination sequences implemented by the scanner.

Interface between the control circuit 36 and the coils of scanner 12 ismanaged by amplification and control circuitry 40 and by transmissionand receive interface circuitry 42. Circuitry 40 includes amplifiers foreach gradient field coil to supply drive current to the field coils inresponse to control signals from control circuit 36. Interface circuitry42 includes additional amplification circuitry for driving RF coil 32.Moreover, where the RF coil serves both to emit the radiofrequencyexcitation pulses and to receive MR signals, circuitry 42 will typicallyinclude a switching device for toggling the RF coil between active ortransmitting mode, and passive or receiving mode. A power supply,denoted generally by reference numeral 34 in FIG. 1 , is provided forenergizing the primary magnet 24. Finally, circuitry 14 includesinterface components 44 for exchanging configuration and image data withsystem control circuitry 16. It should be noted that, while in thepresent description reference is made to a horizontal cylindrical boreimaging system employing a superconducting primary field magnetassembly, the present technique may be applied to various otherconfigurations, such as scanners employing vertical fields generated bysuperconducting magnets, permanent magnets, electromagnets orcombinations of these means.

System control circuitry 16 may include a wide range of devices forfacilitating interface between an operator or radiologist and scanner 12via scanner control circuitry 14. In the illustrated embodiment, forexample, an operator controller 46 is provided in the form of a computerworkstation employing a general purpose or application-specificcomputer. The station also typically includes memory circuitry forstoring examination pulse sequence descriptions, examination protocols,user and patient data, image data, both raw and processed, and so forth.The station may further include various interface and peripheral driversfor receiving and exchanging data with local and remote devices. In theillustrated embodiment, such devices include a conventional computerkeyboard 50 and an alternative input device such as a mouse 52. Aprinter 54 is provided for generating hard copy output of documents andimages reconstructed from the acquired data. A computer monitor 48 isprovided for facilitating operator interface. In addition, system 10 mayinclude various local and remote image access and examination controldevices, represented generally by reference numeral 56 in FIG. 1 . Suchdevices may include picture archiving and communication systems,teleradiology systems, and the like.

FIG. 2 is schematic view of an embodiment of a cooling system 58 (e.g.,thermal management system) coupled to a gradient coil assembly 60 (e.g.,having the gradient coils 26, 28, 30 of FIG. 1 ) of the MRI system 10 ofFIG. 1 . The cooling system 58 includes a cooling cabinet 62 coupled toa manifold assembly 64 (e.g., flexible gradient coil cooling manifoldassembly). The cooling cabinet 62 provides liquid coolant (e.g.,de-ionized water, ethylene glycol, etc.) to the manifold assembly 64.The manifold assembly 64 (via supply lines) provides the liquid coolantto cooling circuits 65 (e.g., jackets, tubes, channels, etc.) disposedwithin the gradient coil assembly 60 to manage the temperature of thegradient coils (e.g., cool the gradient coils). The structure of thecooling circuits 65 may vary based on the gradient structure of thegradient coil assembly 60 and associated gradient coils. After flowingthrough the cooling circuits 65, the liquid coolant is returned to thecooling cabinet 62 via the manifold assembly 64. The cooling cabinet 62may include a heat exchanger to regulate a temperature of the liquidcoolant. As described in greater detail below, the manifold assembly 64includes one or more additively manufactured manifolds or manifoldmodules.

FIGS. 3 and 4 are perspective views of the gradient coil coolingmanifold assembly 64 coupled to the gradient coil assembly 60 (shown indashed outline). The manifold assembly 64 includes a plurality ofadditively manufactured manifold modules or manifolds 66 (e.g.,manifolds 68, 70, 72, 74) plumbed together by flexible rubber hoses 76and secured by clamps 77. Although 4 manifolds 66 are depicted as partof the manifold assembly 64, the number of manifolds 66 may vary (e.g.,1, 2, 3, 4, 5, etc.).

The rubber hoses 76 include a main supply line 78 and a main return line80 for the liquid coolant. Each manifold 66 includes a main or primaryfluid passage 79 coupled to either the main supply line 78 or the mainreturn line 80. In certain embodiments, one or more modules 66 mayinclude two separate main or primary fluid passages 79 coupled to themain supply line 78 and the main return line 80, respectively. Forexample, the manifolds 68 and 70 each include two main fluid passages 79coupled to the main supply line 78 and the main return line 80,respectively. The manifold 72 includes a single main fluid passage 79coupled to the main return line 80. The manifold 74 includes a singlemain fluid passage 79 coupled to the main supply line 78. Theintegration of two main fluid passages 79 (e.g., supply and returnpassages) within a single module for both of the manifolds 68 and 70simplifies the design, reduces leak paths, and saves space. In addition,the respective walls defining two main fluid passages 79 for each of themanifolds 68 and 70 may be coupled together via one or more structuralribs extending between the walls, thus, imparting more strength into theindividual modules to enable them to act as mounting features betweenthe gradient coil assembly 60 and the gradient coil cooling manifoldassembly 64.

Each manifold 66 includes at least one set of secondary fluid passages82 coupled to the main fluid passage 79. In certain embodiments, one ormore modules 66 may include at least one set of secondary fluid passages82 coupled to each of the two separate main or primary fluid passages 79of the module 66. The number of secondary fluid passages 82 in each setmay vary (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.). The secondaryfluid passages 82 are coupled to secondary hoses 84 of the rubber hoses76. The secondary hoses 84 are coupled to either inlets or outlets ofcooling circuits of the gradient coil assembly 60. For example themanifolds 68 and 70 include two or more sets of secondary fluid passages82. The manifolds 72 and 74 include a single set of secondary fluidpassages 82. An inner diameter of the respective wall of each main fluidpassage 79 is greater than respective diameters of the respective wallsof each secondary fluid passage 82 coupled to the respective main fluidpassage 79.

The respective walls (outer surfaces of the walls) of the one or moremain fluid passages 79 and the secondary fluid passages 82 form barbedconnectors or fittings. Each barb connector enables interface with therubber hose 76 and the ability to retain pressurized fluid (e.g. water)via leak-tight connection. A combination of the orientation of the barbson the outer surface of the barbed connectors and post-processing (e.g.,via a vibratory finisher) after additive manufacturing enables the outersurface of the barbed connectors to be leak tight up to pressures of atleast approximately 450 psi (3102 kPa) (which is 3× burst pressure of apressure of approximately 150 psi (1034 kPa)).

As noted above, the manifolds 66 are additively manufactured. Inparticular, the manifolds 66 may be formed as single piece modules viadirect metal laser sintering. The manifolds 66 may be made of anon-ferrous metal (non-magnetized metal) that can hold the necessarypressure (e.g., 450 psi (3102 kPa)). In certain embodiments, themanifolds 66 are made of stainless steel. In other embodiments, themanifolds 66 are made of aluminum. After being additively manufactured,the modules may be subject to post-processing. For example, a vibratoryfinisher may be utilized to optimize the outer surface of barbconnectors on walls defining the secondary fluid passages 82.

The modular design of the gradient coil cooling manifold assembly 64provides many options in both manufacturing and service. For example,failures (e.g., mechanical failures) can be addressed at a module orassembly level. The gradient coil cooling manifold assembly 64 isflexible and the manifolds 66 can be removed or pushed aside to provideaccess to the gradient coil assembly 60. The flexible nature of thegradient coil cooling assembly 64 also provides decoupling between thegradient's high frequency vibration and the manifold 66. Critical space(e.g., axial space 86 (see FIG. 3 ) between the manifold assembly 64 andthe gradient coil assembly 60) is saved by matching the module'smainline geometry to that of the gradient coil assembly's circular shapeand targeting the branches (e.g., secondary fluid passages 82) to theirdestination. In particular, as depicted in FIG. 4 , the main fluidpassage 79 of each manifold 66 is oriented to extend in a direction thatis parallel with and aligned with the annular shape of the gradient coilassembly 60.

FIGS. 5 and 6 are perspective views of an embodiment of the manifold 68of the gradient coil cooling manifold assembly 64 of FIG. 3 . Themanifold 68 includes a first main or primary fluid passage 88 defined bya wall 90 and a second main or primary fluid passage 92 defined by awall 94. Each main fluid passage 88, 92 is open on both ends 95. Thewalls 90 are coupled via structural ribs 96. As depicted, two structuralribs 96 extend between and connect the walls 90, 94. The number ofstructural ribs 96 may vary (e.g., 1, 2, 3, 4, etc.). The first mainfluid passage 88 is configured to couple to the main supply line (e.g.,main supply line 78 in FIG. 3 ). The second main fluid passage 92 isconfigured to couple to the main return line (e.g., main return line 80in FIG. 3 ). The first main fluid passage 88 is fluidly coupled to a set98 of secondary fluid passages 82 (which serve as secondary fluid supplylines coupled to the cooling chambers 65 within gradient coil assembly60 in FIG. 2 ). An inner diameter of the wall 90 of the first main fluidpassage 88 is greater than respective diameters of the respective walls104 of the set 98 of secondary fluid passages 82. The second main fluidpassage 90 is fluidly coupled to a first set 100 of secondary fluidpassages 82 and a second set 102 of secondary fluid passages 82 (each ofwhich serve as secondary fluid return lines coupled to the coolingchambers 65 within the gradient coil assembly 60 in FIG. 2 ). An innerdiameter of the wall 94 of the second main fluid passage 92 is greaterthan respective diameters of the respective walls 104 of each secondaryfluid passage 82 of the first set 100 and second set 102 of secondaryfluid passages 82. As depicted, each set 98, 100, 102 of secondary fluidpassages 82 includes 4 secondary fluid passages 82. Each set 98, 100,102 on opposite sides includes 2 secondary fluid passages 82 thatinitially extend away from the main fluid passage 88 or 92 and thentoward one of the ends 95 of the main fluid passage 88 or 92. Each set98, 100, 102 includes 2 secondary fluid passages 82 branching towardsone end 95 and 2 secondary passages 82 branching towards the oppositeend 95.

Each secondary fluid passage 82 is defined by a respective wall 104. Asdepicted in FIGS. 5 and 6 , an outer surface of each respective wall 104forms a barb connector or fitting 106. An outer surface of each of thewalls 90 and 94 also form barb connectors or fittings 108 at each end95. Each barb connector 106, 108 enables interface with a respectiverubber hose and the ability to retain pressurized fluid (e.g. water) vialeak-tight connection. A combination of the orientation of the barbs onthe outer surface of the barbed connectors 106, 108 and post-processing(e.g., via a vibratory finisher) after additive manufacturing enablesthe outer surface of the barbed connectors 106, 108 to be leak tight upto pressures of at least approximately 450 psi (3102 kPa) (which is 3×burst pressure of a pressure of approximately 150 psi (1034 kPa)).

FIG. 7 is a perspective view of an embodiment of the manifold 70 of thegradient coil cooling manifold assembly 64 of FIG. 3 . The manifold 70includes a first main or primary fluid passage 88 defined by a wall 90and a second main or primary fluid passage 92 defined by a wall 94. Eachmain fluid passage 88, 92 is open on both ends 95. The walls 90 arecoupled via structural ribs 96. As depicted, two structural ribs 96extend between and connect the walls 90, 94. The number of structuralribs 96 may vary (e.g., 1, 2, 3, 4, etc.). The first main fluid passage88 is configured to couple to the main supply line (e.g., main supplyline 78 in FIG. 3 ). The second main fluid passage 92 is configured tocouple to the main return line (e.g., main return line 80 in FIG. 3 ).The first main fluid passage 88 is fluidly coupled to a first set 110 ofsecondary fluid passages 82 and a second set 112 of secondary fluidpassages 82 (each of which serve as secondary fluid supply lines coupledto the cooling chambers 65 within the gradient coil assembly 60 in FIG.2 ). An inner diameter of the wall 90 of the first main fluid passage 88is greater than respective diameters of the respective walls 104 of eachsecondary fluid passage 82 of the first set 110 and the second set 112of secondary fluid passages 82. The second main fluid passage 92 isfluidly coupled to a set 114 of secondary fluid passages 82 (which serveas secondary fluid return lines coupled to the cooling chambers 65within the gradient coil assembly 60 in FIG. 2 ). An inner diameter ofthe wall 94 of the second main fluid passage 92 is greater thanrespective diameters of the respective walls 104 of each secondary fluidpassage 82 of the set 114 of secondary fluid passages 82. As depicted,the sets 110 and 112 of secondary fluid passages 82 includes 4 secondaryfluid passages 82 and the set 114 includes 2 secondary fluid passages82. Each set 110 and 112 includes 2 secondary fluid passages 82 onopposite sides that initially extend away from the main fluid passage 88and then toward one of the ends 95 of the main fluid passage 88. Set 114includes 2 secondary fluid passages 82 that initially extend away fromthe main fluid passage 92 and then toward one end 95 of the main fluidpassage 92. Each set 110 and 112 includes 2 secondary fluid passages 82branching towards one end 95 and 2 secondary passages 82 branchingtowards the opposite end 95.

Each secondary fluid passage 82 is defined by a respective wall 104. Asdepicted in FIG. 7 , an outer surface of each respective wall 104 formsa barb connector or fitting 106. An outer surface of each of the walls90 and 94 also form barb connectors or fittings 108 at each end 95. Eachbarb connector 106, 108 enables interface with a respective rubber hoseand the ability to retain pressurized fluid (e.g. water) via leak-tightconnection. A combination of the orientation of the barbs on the outersurface of the barbed connectors 106, 108 and post-processing (e.g., viaa vibratory finisher) after additive manufacturing enables the outersurface of the barbed connectors 106, 108 to be leak tight up topressures of at least approximately 450 psi (3102 kPa) (which is 3×burst pressure of a pressure of approximately 150 psi (1034 kPa)).

FIG. 8 is a perspective view of an embodiment of the manifold 72 of thegradient coil cooling manifold assembly 64 of FIG. 3 . The manifold 72includes a single main or primary fluid passage 92 defined by a wall 94.The main fluid passage 92 is open on one end 95 and closed on theopposite end 95. The main fluid passage 92 is configured to couple tothe main return line (e.g., main return line 80 in FIG. 3 ). The mainfluid passage 92 is fluidly coupled to a first set 116 of secondaryfluid passages 82 and a second set 118 of secondary fluid passages 82(each of which serve as secondary fluid return lines coupled to thecooling chambers 65 within the gradient coil assembly 60 in FIG. 2 ). Aninner diameter of the wall 94 of the main fluid passage 92 is greaterthan respective diameters of the respective walls 104 of each secondaryfluid passage 82 of the first set 116 and the second set 118 ofsecondary fluid passages 82. As depicted, the sets 116 and 118 ofsecondary fluid passages 82 each include 4 secondary fluid passages 82.Each set 116 and 118 includes 2 secondary fluid passages 82 on oppositesides that initially extend away from the main fluid passage 88 and thentoward one of the ends 95 of the main fluid passage 88. Each set 116 and118 includes 2 secondary fluid passages 82 branching towards the openend 95 and 2 secondary passages 82 branching towards the closed end 95.

Each secondary fluid passage 82 is defined by a respective wall 104. Asdepicted in FIG. 8 , an outer surface of each respective wall 104 formsa barb connector or fitting 106. An outer surface of the wall 94 forms abarb connector or fitting 108 on the open end 95. Each barb connector106, 108 enables interface with a respective rubber hose and the abilityto retain pressurized fluid (e.g. water) via leak-tight connection. Acombination of the orientation of the barbs on the outer surface of thebarbed connectors 106, 108 and post-processing (e.g., via a vibratoryfinisher) after additive manufacturing enables the outer surface of thebarbed connectors 106, 108 to be leak tight up to pressures of at leastapproximately 450 psi (3102 kPa) (which is 3× burst pressure of apressure of approximately 150 psi (1034 kPa)).

FIG. 9 is a perspective view of an embodiment of the manifold 74 of thegradient coil cooling manifold assembly 64 of FIG. 3 . The manifold 74includes a single main or primary fluid passage 88 defined by a wall 90.The main fluid passage 88 is open on one end 95 and closed on theopposite end 95. The main fluid passage 88 is configured to couple tothe main supply line (e.g., main supply line 78 in FIG. 3 ). The mainfluid passage 88 is fluidly coupled to a set 120 of secondary fluidpassages 82 (each of which serve as secondary fluid supply lines coupledto the cooling chambers 65 within the gradient coil assembly 60 in FIG.2 ). An inner diameter of the wall 90 of the main fluid passage 88 isgreater than respective diameters of the respective walls 104 of eachsecondary fluid passage 82 of the set 120 of secondary fluid passages82. As depicted, the set 120 of secondary fluid passages 82 includes 6secondary fluid passages 82 circumferentially distributed about andextending toward the closed end 95 of the main fluid passage 88.

Each secondary fluid passage 82 is defined by a respective wall 104. Asdepicted in FIG. 9 , an outer surface of each respective wall 104 formsa barb connector or fitting 106. An outer surface of the wall 90 forms abarb connector or fitting 108 on the open end 95. Each barb connector106, 108 enables interface with a respective rubber hose and the abilityto retain pressurized fluid (e.g. water) via leak-tight connection. Acombination of the orientation of the barbs on the outer surface of thebarbed connectors 106, 108 and post-processing (e.g., via a vibratoryfinisher) after additive manufacturing enables the outer surface of thebarbed connectors 106, 108 to be leak tight up to pressures of at leastapproximately 450 psi (3102 kPa) (which is 3× burst pressure of apressure of approximately 150 psi (1034 kPa)).

Technical effects of the disclosed embodiments include providing agradient coil cooling manifold assembly that includes one or moreadditively manufactured manifold modules. The additively manufacturedmanifold modules include complex geometries that enable them to beoptimized to produce maximum flow with minimal volumetric space,efficient fabrication, assembly, and service ability. Critical space(e.g., axial space between the manifold assembly and the gradient coilassembly) is saved by matching the module's mainline geometry to that ofthe gradient coil's circular shape and targeting the branches to theirdestination. Fabricating this complex geometry would be substantiallymore difficult with traditional module fabrication techniques. Additivemanufacturing allows combining otherwise separate components into asingle part enable to withstand the system parameters for cooling agradient coil assembly of a MRI system. The disclosed embodiments enableless connections in the manifold assembly, thus, lowering the risk ofleaks. In addition, less braze joints/fittings enables a lower risk ofmechanical failure in the manifold assembly. Further, the custom precisegeometry enables better cooling with fewer failures. Even further, thedisclosed embodiments enable a lower cost manifold assembly.

The techniques presented and claimed herein are referenced and appliedto material objects and concrete examples of a practical nature thatdemonstrably improve the present technical field and, as such, are notabstract, intangible or purely theoretical. Further, if any claimsappended to the end of this specification contain one or more elementsdesignated as “means for [perform]ing [a function] . . . ” or “step for[perform]ing [a function] . . . ”, it is intended that such elements areto be interpreted under 35 U.S.C. 112(f). However, for any claimscontaining elements designated in any other manner, it is intended thatsuch elements are not to be interpreted under 35 U.S.C. 112(f).

This written description uses examples to disclose the present subjectmatter, including the best mode, and also to enable any person skilledin the art to practice the subject matter, including making and usingany devices or systems and performing any incorporated methods. Thepatentable scope of the subject matter is defined by the claims, and mayinclude other examples that occur to those skilled in the art. Suchother examples are intended to be within the scope of the claims if theyhave structural elements that do not differ from the literal language ofthe claims, or if they include equivalent structural elements withinsubstantial differences from the literal languages of the claims.

1. A manifold for a gradient coil cooling manifold assembly of amagnetic resonance imaging (MRI) system, comprising: a first main fluidpassage defined by a first wall; and a first set of secondary fluidpassages coupled to the first main fluid passage and defined byrespective walls, wherein the first wall of the first main fluid passageand the respective walls of the first set of secondary fluid passagesform barb connectors configured to couple to respective hoses; whereinthe manifold is formed as a single integral piece.
 2. The manifold ofclaim 1, wherein the manifold is additively manufactured.
 3. Themanifold of claim 1, wherein respective outer surfaces of the respectivewalls of the first set of secondary fluid passages are configured to beleak tight to pressures greater than approximately 3102 kilopascals whencoupled to the respective hoses.
 4. The manifold of claim 1, wherein thegradient coil cooling manifold assembly is configured to couple to agradient coil assembly having an annular shape, and wherein the firstmain fluid passage is oriented to extend in a direction that is parallelwith the annular shape of the gradient coil assembly when the gradientcoil cooling manifold assembly is coupled to the gradient coil assembly.5. The manifold of claim 1, wherein the first main fluid passagecomprises a fluid inlet.
 6. The manifold of claim 1, wherein the firstmain fluid passage comprises a fluid outlet.
 7. The manifold of claim 1,wherein an inner diameter of the first wall of the first main fluidpassage is greater than respective diameters of the respective walls ofthe first set of secondary fluid passages.
 8. The manifold of claim 1,comprising a second main fluid passage defined by a second wall, whereinthe second main passage is separate from the first main passage.
 9. Themanifold of claim 8, comprising a second set of secondary fluid passagescoupled to the second main fluid passage and defined by additionalrespective walls, wherein the additional respective walls of the secondset of secondary fluid passages each form additional barb connectorsconfigured to couple to additional respective hoses.
 10. The manifold ofclaim 8, comprising one or more ribs extending between the first walland the second wall.
 11. The manifold of claim 8, wherein the first mainfluid passage and the second main fluid passage are parallel with eachother.
 12. The manifold of claim 8, wherein the first main passagecomprises a fluid inlet and the second main passage comprises a fluidoutlet.
 13. A gradient coil cooling manifold assembly of a magneticresonance imaging (MRI) system, comprising: a plurality of hoses; and aplurality of additively manufactured manifolds coupled to the pluralityof hoses, wherein each additively manufactured manifold of the pluralityof additively manufactured manifolds comprises: a main fluid passagedefined by a wall; and a set of secondary fluid passages coupled to themain fluid passage and defined by respective walls, wherein the wall ofthe main fluid passage and the respective walls of the set of secondaryfluid passages form barb connectors configured to couple to respectivehoses of the plurality of hoses.
 14. The gradient coil cooling manifoldassembly of claim 13, wherein each additively manufactured manifold ofthe plurality of additively manufactured manifolds is formed as a singleintegral piece.
 15. The gradient coil cooling manifold assembly of claim13, wherein the gradient coil cooling manifold assembly is configured tocouple to a gradient coil assembly having an annular shape.
 16. Thegradient coil cooling manifold assembly of claim 15, wherein the mainfluid passage is oriented to extend in a direction that is parallel withthe annular shape of the gradient coil assembly when the gradient coilcooling manifold assembly is coupled to the gradient coil assembly. 17.The gradient coil cooling manifold assembly of claim 15, wherein aflexibility of the gradient coil cooling manifold assembly is configuredto decouple the gradient coil cooling manifold assembly from mechanicalvibrations of the gradient coil assembly when coupled the gradient coilcooling manifold assembly is coupled to the gradient coil assembly. 18.A magnetic resonance imaging (MRI) system, comprising: a gradient coilassembly comprising a plurality of gradient coils; a gradient coilcooling manifold assembly configured to couple to the gradient coilassembly and to regulate a temperature of the gradient coil assembly,wherein the gradient coil cooling manifold assembly comprises aplurality of manifolds, wherein each manifold of the plurality ofmanifolds comprises: a main fluid passage defined by a wall; and a setof secondary fluid passages coupled to the main fluid passage anddefined by respective walls, wherein the wall of the main fluid passageand the respective walls of the set of secondary fluid passages formbarb connectors configured to couple to respective hoses; wherein eachmanifold of the plurality of manifolds is formed as a single integralpiece.
 19. The MRI system of claim 18, wherein each manifold of theplurality of manifolds is additively manufactured.
 20. The MRI system ofclaim 18, wherein respective outer surfaces of the respective walls ofthe set of secondary fluid passages are configured to be leak tight topressures greater than approximately 3102 kilopascals when coupled tothe respective hoses.